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(T. F. “Storm” Walsh)
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Please be aware, even though I do not post every night, rest assured I am continuously monitoring various areas for any significant weather. I will be taking Sundays off (family time), unless we have active systems that may be posing a threat (i.e. Tropical, Winter Weather, Coastal Storms, etc.).
I will reiterate, my forecasts are based on the available information at the time of analysis, and are only as accurate as the information analyzed and the solutions provided.
The Storm Prediction Center (SPC), has issued an ENHANCED RISK OF SEVERE THUNDERSTORMS in the current DAY 2 outlook: ACROSS PORTIONS OF THE SOUTHERN PLAINS…
A severe threat is expected to develop Monday over the southern and central Plains eastward into the Ozarks. Large hail, wind damage and tornadoes will be possible Monday afternoon and evening. A marginal severe threat will also be possible across parts of west-central Texas, western Tennessee Valley, and portions of southern Idaho.
A mid-level trough will traverse the southern Plains tomorrow/Monday, encouraging surface low deepening near the Oklahoma panhandle. A moist, buoyant airmass will be drawn northward across portions of the southern Plains into the Ozark Valley through the day. As instability increases with the onset of both diurnal heating and northward moisture advection, thunderstorms are expected to increase in both coverage and intensity along the warm front in the Arklatex/Ozark regions, and ahead of the dryline from central Kansas to central Texas tomorrow afternoon. All facets of severe will be possible across the south-central U.S. In addition, enough buoyancy is expected to develop ahead of a 500 mb speed max/surface lee-trough across portions of southern Idaho to support a marginal severe threat during the afternoon.
SPC DAY 2 CONVECTIVE OUTLOOK LINK:
SPC DAY 2 CONVECTIVE OUTLOOK
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 – EF5 tornadoes within 25 miles of a point.
Probability of one inch diameter hail or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of two inch diameter hail or larger within 25 miles of a point.
DAMAGING THUNDERSTORM WIND PROBABILITY
Based on my analysis of the SPC DAY 2 Outlook, the thermodynamic setup will allow for all hazards. Analysis of the forecast setup indicates a sharpening, trailing dryline from central KS into OK., and a portion of NW TX. This feature, combined with steep mid level lapse rates (analyzed), MLCAPE of 2000 j/kg or higher, low to mid 60F dewpoints, strengthening LLJ, and effective bulk shear of 40-60 kts could allow for strong/significant tornadoes (EF2+), and significant hail (2+ inches in diameter) over the enhanced risk outline, beginning by late afternoon
Based on my analysis of both the NAM-WRF model from F5 DATA, and the NAM 3 km model, the following forecast severe and tornado indices were analyzed and values represent a blend of both models:
SBCAPE: 1500 – 3000 j/kg
MLCAPE: 1000 – 2000 j/kg
SRH: 200 – 450 m2/s2
L. I.: -2 to -6
SWEAT: 300 – 450
EHI: 2 – 5
VGP: 0.2 – 0.6
STP: 1 – 4
A majority of significant tornadoes (F2 or greater damage) have been associated with STP values greater than 1, while most non-tornadic supercells have been associated with values less than 1 in a large sample of RAP analysis proximity soundings.
A multiple ingredient, composite index that includes effective storm-relative helicity (ESRH, based on Bunkers right supercell motion), most unstable parcel CAPE (muCAPE) and convective inhibition (muCIN), and effective bulk wind difference (EBWD). Each ingredient is normalized to supercell “threshold” values, and larger values of SCP denote greater “overlap” in the three supercell ingredients. Only positive values of SCP are displayed, which correspond to environments favoring right-moving (cyclonic) supercells.
VGP: The VGP(Vorticity Generation Parameter) is meant to estimate the rate of tilting and stretching of horizontal vorticity by a thunderstorm updraft. Values greater than 0.2 m s-2 suggest an increasing possibility of tornadic storms.
The following sites will explain most of these values, and will give you an idea of what to expect:
ENVIRONMENTAL INDICES AND PARAMETERS NWS
THE WEATHER PREDICTION
The following outlined areas indicate where the modeling suggests the best / highest probabilities for the strongest severe weather and tornadoes could occur. The strongest of the indices will be located where the SPC has the 10% hatched area probability for tornadoes. Based on analysis of the indices, the values begin to increase at around 4:00 p. m. CDT, and peak between this time and 10:00 p. m. CDT, then begin to weaken thereafter. There was a glitch this evening in the STP and SCP animations, so I will be posting static maps of the STP and SCP values from Earl Barker’s site Weather Caster:
F5 DATA NAM – WRF 4:00 P. M. CDT
7:00 P. M. CDT
10:00 P. M. CDT
The following NAM 3km static maps indicate the locations and strength of the forecast STP (Significant Tornado Parameter) index, and SCP (Supercell Composite Parameter) index.
NAM 3km STP (4:00 P. M. CDT MAY 02 – 10:00 P. M. CDT MAY 02)
NAM 3km SCP
Please use the following maps for all days, which should update automatically, for Mesoscale Discussions and Convective Watches. You may have to refresh your browser, or click on the graphics. I am also providing the SPC homepage link, so you may get the updated information regarding any changes to the outlook:
SPC MESOSCALE DISCUSSIONS (CLICK IMAGE FOR UPDATES)
SPC CONVECTIVE WATCHES (CLICK IMAGE FOR UPDATES)
SPC HOMEPAGE LINK
IF A TORNADO WARNING IS ISSUED FOR YOUR AREA, IMMEDIATELY TAKE STURDY AND SAFE SHELTER
The following NWS Watch / Warning map will provide local NWS information for your area. Click the image, then once it refreshes, click on your area of interest to view any special weather statements, hazards or advisories for your area.
NWS WATCH / WARNING DISPLAY (LINKED…CLICK MAP, THEN YOUR AREA)
WSI DOPPLER RADAR LOOP (LINKED)
RAP RADAR (CLICK IMAGE THEN RADAR SITE)
You may direct any questions by contacting me personally, ANYTIME, at: firstname.lastname@example.org
Have a blessed evening!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
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